Adjustable support arms are typically utilized for mounting objects such as a flat panel displays, light sources, or work surfaces. Many adjustable support arms utilize a gas cylinder to counterbalance the weight of an attached object. However, in addition to being heavy and bulky, gas cylinders are prone to failure. Moreover, gas cylinders inevitably leak gas and lose pressure and, therefore, have a limited lifespan.
Mechanical springs have been used as an alternative to gas cylinders in adjustable support arms. Support arms utilizing mechanical springs are generally lighter, more compact, and less costly to manufacture and maintain than support arms featuring gas cylinders without sacrificing strength and weight-load capacity. However, mechanical springs present their own performance issues. Typically, one end of a mechanical spring is attached to an upper link of the support arm, while the second end of the spring is attached to a lower link. Yet, when the support arm is brought to its highest vertical position or its lowest vertical position, the spring can be extended beyond a range that is within the tolerances of the spring, causing the spring to exhibit non-linear characteristics. This may be evidenced by a sagging effect when the support arm is brought to its highest position and a creeping effect when the support arm is brought to its lowest position. Repeated over-extension of the spring can ultimately result in spring fatigue or permanent spring deformation.
Additionally, generation adjustable support arms typically utilize frictional forces to supplement the counterbalancing force provided by the gas cylinder or mechanical spring to offset the applied load throughout the support arm's range of motion.